1. Field of the Invention
The present invention relates to a manufacturing process of semiconductor device. More particularly, the present invention relates to a sputtering apparatus and a manufacturing method of metal/metal compound layer by using the sputtering apparatus.
2. Description of Related Art
In a process of semiconductor metallization, due to ever increased high degree of integration, it is often required to form a structure with multilevel interconnects, where each metal layer is insulated from the other layers via insulation layers, and different metal layers are connected with conductive plugs.
Aluminum and tungsten are so far the most important and frequently used metals in metallization processes. In prior art, aluminum is formed via magnetron DC sputtering and, due to its low resistivity, is primarily used as conducting wire between semiconductor devices. Tungsten is formed via chemical vapor deposition (CVD) and, due to its superior property for multi-layer covering and easiness for etching, is primarily used as conductive plug for filling into contact or via openings. However, aluminum causes a phenomenon of spiking, while tungsten is not desirable due to its adhesive property on substrates. Thus, in order to avoid spiking associated with aluminum and enhance adhesion of tungsten with the insulating layer on two sidewalls and with the metal layer under tungsten, a conductive material called barrier layer is often formed between the metal of aluminum or tungsten and other materials.
Titanium nitride is currently one of the most frequently used materials as barrier layers in very large scale integration process (VLSI). Further, for enhancing the capability of Ohmic Contact of a metal on silicon, titanium nitride barrier layer as used in a process to form a contact metal is utilized in combination with titanium in a form of titanium/titanium nitride. In processes to form contact metals, titanium and titanium nitride are formed via physical vapor deposition (PVD).
One of the methods in prior art to form titanium/titanium nitride is magnetron DC sputtering by depositing a titanium layer on a wafer, where the gas being used is argon and titanium is deposited with a thickness of about 200 xc3x85. Afterwards, reactive sputtering is carried out in the same chamber to form a layer of titanium nitride on the titanium layer, where the gases being used are nitrogen and argon, and titanium nitride is deposited with a thickness of about 400 xc3x85. In the above method, titanium layer and titanium nitride layer are formed in the same chamber, and thus titanium nitride particles will be deposited on the wafer to cause problems on quality of products.
To solve such problem of deposition of titanium nitride particles, methods employed in prior art include changing roughness of process kits, changing magnetic distribution of the apparatus, enhancing quality of target, improving conditions of hardware (e.g., gas pipelines) and modifying purge formulas. However, all of the forgoing methods fail to effectively reduce the deposition of titanium nitride particles and have problems such as high costs and low productivity.
In view of the foregoing, the present invention provides an apparatus and a manufacturing method of metal layer, for reducing the deposition of titanium nitride particles, avoiding adhesion of titanium nitride particles, and to improve adhesive property of titanium and titanium nitride.
According to one object of the present invention is to provide a sputtering apparatus capable of maintaining the reaction temperature within the chamber substantially uniform. According to another object of the present invention is to provide a water-cooling system that is capable of controlling the inner sidewall of the chamber for rendering the reaction temperature within the chamber substantially uniform.
According to another object of the present invention is to provide a manufacturing method of forming metal/metal compound layer using sputtering apparatus of the present invention so that the adhesion property of the metal/metal compound layer can be effectively promoted.
According to another object of the present invention is to provide a manufacturing method of forming metal/metal compound layer using sputtering apparatus of the present invention so that the number of particle deposition on the wafer can be substantially reduced.
In accordance with the above objects and other advantages of the present invention, a sputtering apparatus, and a manufacturing method of forming a metal/metal compound layer is provided. The sputtering apparatus includes a chamber, a cathode, a power-supplying device, a metal target, a wafer-supporting device, a pressure-reducing device, a gas-supplying device, a temperature-measuring device and a water-cooling system. The cathode is installed on the top of the chamber. The power-supplying device is connected to the cathode. The metal target is installed on the cathode. The wafer-supporting device, on which a wafer can be held, is installed in the chamber and is coaxial with and parallel to the metal target. The pressure-reducing device is connected to the chamber to keep the vacuum in the chamber on a certain level. The gas-supplying device is connected to the chamber to supply gases to the chamber. The temperature-measuring device includes a temperature sensor and a temperature receiver. The temperature sensor is installed on the inner sidewall of the chamber to measure the sidewall temperature of the chamber. The temperature receiver is connected to the temperature sensor to receive and store the temperature data measured by the temperature sensor. The water-cooling system includes cooling water piping and a temperature controlling device of the chamber. The cooling water piping encircles on the sidewalls of the chamber. The temperature controlling device of the chamber is connected to the cooling water piping and the temperature sensor to supply cooling water into the cooling water piping and to adjust flow rate of the cooling water to control temperature of the inner sidewalls of the chamber based on temperature signals received from the temperature receiver.
A magnetron device is installed in the cathode of the foregoing sputtering apparatus. The power-supplying device is a high-voltage DC power supplier, and the temperature sensor is a thermo couple. As installed in the sputtering apparatus to measure the sidewall temperature of the chamber, the temperature-measuring device can be utilized in a sputtering process for feedback control of the water-cooling system to keep inner wall temperature of the chamber at about 50xc2x0 C.xcx9c70xc2x0 C., for reducing the difference of temperature distribution in the chamber, and thereby improving adhesive property of titanium and titanium nitride, and reducing the deposition of titanium nitride particles.
The present invention further provides a manufacturing method of metal layer/metal compound layer. A wafer is first placed in a chamber. After forming a metal layer on the wafer in the same chamber, a metal compound layer is subsequently formed over the metal layer. During the process of forming the metal layer and the metal compound layer, the sidewall temperature of the chamber is controlled at about 50xc2x0 C.xcx9c70xc2x0 C.
In the foregoing method, the metal layer is formed with the material of titanium via magnetron DC sputtering, whereas the metal compound layer is formed with the material of titanium nitride via reactive sputtering. The sidewall temperature of the chamber is controlled at about 50xc2x0 C.xcx9c70xc2x0 C. by measuring the sidewall temperature of the chamber, based on which, the flow rate of cooling water can be adjusted for controlling the sidewall temperature.
According to a principal aspect of manufacturing method of metal layer/metal compound layers of the present invention, during the formation of the metal/metal nitride layers, the sidewall temperature of the chamber is controlled at about 50xc2x0 C.xcx9c70xc2x0 C. in order to reduce the difference of temperature distribution in the chamber so as to improve adhesive property of the metal layer and the metal compound layer, and reduce the deposition of metal compound particles.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.